Headlines like these have become increasingly common in recent years. They refer to the results of the PACE trial, a government-funded study into the safety and efficacy of graded exercise and cognitive behavioural therapies (GET/CBT) as treatments for ME.

The trial ostensibly showed that structured exercise can be used to treat ME, but ME specialists condemn the research as flawed, misleading and potentially harmful. No one denies the importance of patients remaining as active as possible within safe limits; the question is whether goal-focussed programmes that push against those limits are helpful or harmful when it comes to ME.

1. PACE promotes the theory that ME has a primarily psychosocial cause

Despite substantial evidence for the physical basis of ME, psychiatrists behind the PACE trials believe it to be a form of personality disorder perpetuated by psychosocial factors.

Results of PACE seem very different to patient experiences of graded exercise. Surveys of patients found the majority claim to have had no benefit from exercise or to have wound up sicker, yet the PACE trial claimed 60% of participants improved.

Physical exertion has been repeatedly shown to have a measurable effect on patients with ME, causing muscle abnormalities, neurocognitive impairments, decreased motor speed, poor reaction times, reduced peak flow and abnormal brain activity. People with ME have a reduced capacity to recover from exertion and this exercise intolerance has a cumulative effect until patients reach a point where their capacity for exertion actually decreases.

The PACE researchers acknowledge that poorly-delivered graded exercise can make patients worse but the UK has very few physiotherapists qualified to deliver specialist care.

3. Patient selection for the PACE trials was extremely controversial

The PACE trials were based upon the Oxford criteria for CFS/ME, which focuses on fatigue as the primary symptom. The focus on idiopathic fatigue means patients with misdiagnosed or co-morbid psychiatric diagnoses (such as depression, anxiety, and somatoform disorders) were not excluded from the trial. All these disorders are known to cause fatigue and to respond to exercise and CBT.

By the PACE researchers’ own reckoning only 67% of patients met the American CDC criteria for CFS and only 51% met the London Criteria which focuses on the exercise-induced fatigue required for diagnosis in the UK. Patients with primary symptoms other than fatigue were excluded from the trial as were children and anyone with severe ME, meaning its results cannot be extrapolated beyond a certain subgroup of patients. This is particularly important as many doctors (and the media) attempt to apply the results universally.

4. Data from the trial has been widely misrepresented

Two forms of assessment were used to measure patients’ fatigue in the trial: subjective patient questionnaires and an objective six-minute walking test. Figures quoted in the press were based upon patient perceptions of fatigue but the extent of perceived improvement was not substantially upheld in physical tests.

At the start of the trial, patients averaged a distance of approximately 300 meters in a six-minute walking test. The authors of the trial proposed a forty-five meter improvement as providing a ‘clinically useful’ outcome. The group that received medical care alone improved by twenty meters while the group that received graded exercise improved by thirty-five. As the graded exercise was in addition to medical care however, the first twenty meters of improvement may be attributed to this, meaning only fifteen meters can be attributed to the exercise itself. Few people would deny that a fifteen meter improvement after a year of therapy is hardly a miracle cure.

The furthest distance completed in the walking test was only half the average distance of a typical healthy pensioner. Fatigue levels were still higher at the end of the trial than for patients with congestive heart failure.

As fatigue is only one of many disabling symptoms of ME, a reduction in fatigue does not necessarily equate to a return to health or improvement in physical and social function. No data about patient recovery or deterioration has yet been published, so media claims that patients were ‘cured’ or returned to ‘normal’ following the trial are unsupported. There is no evidence that patients came off benefits or returned to work as a result of the trial, in fact receipt of benefits was found to have increased. Given ME is characterised by periods of remission and relapse it will be interesting to see whether improvements are sustained in the longer-term.